1. Field of the Invention
This invention relates generally to a system and method for disposing a liner material inside of a container or pipe. More specifically, the present invention enables the construction of a pressure vessel having an inner liner, where the pressure vessel and the inner liner are comprised of two different materials, and wherein there is an advantage to manufacturing the pressure vessel from the two different materials.
2. Description of Related Art
In general, a pressure vessel is a storage tank or vessel that has been designed to operate at pressure. Inspections of pressure vessels have shown that there are often a considerable number of cracked and damaged vessels in operation at workplaces. Cracked and damaged pressure vessels can result in leakage or rupture failures. These failures may be catastrophic, defined as causing damage to property or people in the vicinity. Potential health and safety hazards of leaking vessels include poisonings, suffocations, fires, and explosion hazards. Rupture failures are typically much more catastrophic than leaks, and can cause considerable damage to life and property. The safe design, installation, operation, and maintenance of pressure vessels in accordance with appropriate codes and standards are essential to worker safety and health, and protection of the environment.
Common materials held and maintained by pressure vessels include air, water, nitrogen, refrigerants (like Freon), ammonia, propane, and reactor fuels. Due to the pressurizing capabilities of pressure vessels, they are often used to store chemicals and elements that can change states (most notably gases that have been liquidized). In most cases, the walls of pressure vessels are thicker than normal tanks, and thus providing greater protection for people and property when in use with hazardous or explosive materials.
Pressure vessels are used in a variety of industries including chemical, cosmetics, food and beverage, oil/fuel, transportation, paper and pulp, pharmaceutical and plastic processing, and power generation.
Many pressure vessels have built-in temperature control characteristics (heating only, cooling only or both heating and cooling) in addition to pressurizing capabilities. This can help to keep volatile chemicals in relatively inert states, or when necessary, change the state of the material to prepare it for transportation or use in a connected system.
Pressure sources for pressure vessels are limited to the maximum allowable working pressure of the lowest rated system component. When sources cannot be limited, the use of pressure-relief devices is required. Common relief devices include spring-loaded relief valves and rupture disc assemblies. Additional precautions such as audible alarms and computer regulation are often necessary in systems where pressure relief is necessary, especially if the material being contained is hazardous in nature.
To increase the strength and the lifetime of pressure vessels, some pressure vessels are manufactured using expensive or more exotic materials. For example, the costly material titanium can be used for the entire pressure vessel. However, the cost of a large titanium pressure vessel can be prohibitive. Thus, many pressure vessels are manufactured using two or more different materials in layers. For example, an inner liner material may provide needed corrosion resistance, while an outer layer or shell may provide strength to keep the pressure vessel intact when pressurized. The inner liner protects the outer shell from corrosion, while the outer shell prevents the inner liner from being physically breached.
The attachment of an inner liner to an outer shell can be accomplished using traditional welding techniques or mechanical fixturing. Disadvantageously, conventional techniques such as arc welding are not performed as a solid state process, resulting in problems in heat affected zones. These problems include corrosion and cracking that can result in failure of the pressure vessel.
Other methods known to those skilled in the art for improving pressure vessels include cladding and surface treating.
It is interesting to note that in many cases there are many regulations regarding the materials and processes that can be used to manufacture pressure vessels for particular industries. These regulations have the unintended disadvantage of also functioning to prohibit innovation in materials and processes used in pressure vessel construction.
Accordingly, it would be an advantage over the state of the art to provide a system and method for creating improved pressure vessels, pipes, and other containers. It would also be an advantage to provide a system and method that can pass the requirements of existing regulations so that no new certification and testing processes are necessary.